| 摘要 |
PURPOSE:To prevent obstruction due to abnormal voltage impression at the time of no load when the discharge lamp concerned is in its final period of lifetime by providing a device which lights up the discharge lamp using a stabilizer including a switching element, and constituting this device from a means to sense the lamp voltage and a means to control the output of a stabilizer in compliance with the sensed voltage of battery. CONSTITUTION:The output of an AC power supply 2A being the power to light up a high voltage discharge lamp 1 is converted into a DC current by a rectifier/smoother circuit 2 consisting of a diode bridge 7 and capacitor 8, and the resultant is subjected to power control with a chopper circuit consisting of a switching element of an FET 3, wherefrom high frequency ripples are removed by a smoother circuit 4 composed of a diode 9, choke coil 10, and capacitor 11. From this smoother circuit 4, the lamp voltage of the discharge lamp 1 is taken out and given to a Schmit trigger circuit 5, and if the lamp voltage exceeds the reference voltage 13, the corresponding output is given to a control circuit 6, and the FET 3 of the chopper circuit is controlled in accordance with the output of the control circuit 6, and in compliance with the output therefrom the FET 3 of the chopper circuit is controlled and a requisite current is fed to the discharge lamp 1. |
